September in the garden

Give your roses some attention in September. Image: Thinkstock

Flowers

• Spring annuals are at their peak, but to stay that way need regular attention. Snip off faded flowers regularly, vital with pansies, poppies and polyanthus, and add them to the compost heap.

• Flowers bloom merely to make seed and ensure another year's survival. Frustrate them by removing the seedheads and they must produce more flowers. Snip away excess tangled growth of nemesia, sweet peas and violas for a prolonged display, too.

• Annuals in bloom should be fed regularly with soluble fertiliser. Always water plants before and after feeding to prevent fertiliser burning roots.

• Order new chrysanthemum plants and prepare beds. Select a sunny well-drained site sheltered from strong winds. Dig over several times working in compost and manure. Apply a light dressing of complete fertiliser about two weeks before planting. Chrysanthemum cuttings can be set out ready to transplant next month.

• Check that new growth on roses is going in the right direction. If not, cut back to a suitably placed lower bud. Check new buds for insects and treat promptly. Fork soil over lightly under rose bushes and add a liberal topdressing of well-rotted manure.

Trees and shrubs

• Deciduous shrubs which recently flowered on bare wood in winter or early spring eg: japonica, forsythia, weigela and flowering cherry, should be pruned immediately after bloom.

• Shrubs flowering later in spring or summer on new shoots eg: oleander and fuchsia, should be pruned early this month before new growth begins. Cut poinsettias and oleanders back fairly hard. Shrubs that form dense clumps of canes, such as japonicas and forsythia, should have about a third of the oldest canes cut out entirely, the rest shortened by about a third.

• Thin out cane-stemmed shrubs such as abelia, deutzia, kolkwitzia and may (spiraea), removing exhausted canes almost to the ground. Cut bouvardia almost to the ground, then keep pinching new shoots until February to form a neat, bushy, free-blooming shrub. A complete, slow-release fertiliser helps maintain good growth.

• Feed NSW Christmas bush well; mature trees can absorb a whole bucket of cow manure, or better still, poultry manure, provided it is well-aged. Rake it all around the spread of the outer branches and water in. Deep soak these bushes from now on.

• Ornamental trees and shrubs will benefit from suitable fertiliser.

• Feed acid-loving plants such as andromeda (pieris), azaleas, camellias, daphne and rhododendron only after they have finished flowering (fertiliser encourages leaf growth here at the expense of flowers). Use either packaged camellia and azalea food or well-rotted cow manure. If the latter, spread a thick layer under the foliage canopy but don't build it up around the trunk as this can cause collar rot.

• Feed gardenias, particularly if their leaves are yellowing, with plenty of old animal manure - cow, horse or poultry - and water in well, adding a tablespoon of Epsom salts to each bucket. Leaf yellowing should soon fade, but if not suspect root nematodes. Consult your local nursery.

In the Veggie patch

• Plant seedlings of beetroot and lettuce.

• Plant potatoes.

• Set your kids a challenge to grow a giant pumpkin. Get them to help you prepare a well dug site that gets plenty of sun and has good drainage. You can buy giant pumpkin seeds online from companies such as Atlantic Seeds.

• Start applying mulch to help beds conserve moisture over summer and to prevent weeds. Among the best mulches are the organic ones such as lucerne hay, pea straw and sugar cane, which break down to improve the soil quality and to encourage earthworms. In bushfire-prone areas it’s best to stick to inorganic mulches, such as pebbles and gravels, which won’t ignite.

Control pests

• Watch azaleas for fleshy pale green to white leaves. This is the fungus disease, leaf gall. Cut off affected leaves, drop straight into a bag and throw out to limit the spread. Protect azaleas against petal blight (pale circular spots on the petals, which become limp and hang on the plant). Pick and burn all dead flowers from diseased plants regularly to prevent spread and carry-over of spores.

• Root nematodes (mostly in sandy soils) attack gardenias. The remedy? Plant marigolds (tagetes) alongside.

• Spray for bindii in the lawn with-a selective weedicide. Sprinkling straight sulphate of ammonia kills most other weeds.

• Spray for red spider and lace bug on azalea, fuchsia and viburnum.

• Remove snails around seedlings, acanthus and cliveas.

• Protect new rose shoots against aphids.

• Peaches and nectarines are most susceptible to leaf-curl so spray at pink bud stage.

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